What type of resistor do I need?

If all else fails wire two of the proper bulbs into the circuit and hide them somewhere. That way you won't have to worry about fooling the bulb failure module for the bulbs will actually be in the circuit. That may be a crude way but it will work. I do know that on some of those modules you have to have bulbs of the same age, and sometimes of a given manufacturer, like syvania or wagner. Sometimes the amount of current is accounted for, other times just the current balance between the two lamp assemblies.

I'm upgrading the tail lamps on my vehicle and one set of bulbs are not being used in the new configuration. However, these two bulbs were monitored by the vehicle's bulb failure system.

I'd like to exchange the bulbs with two resistors (to trick the Bulb Failure Module), but I'm not sure what kind to use.

They are 5 Watt bulbs.

Thanks

-John

monitored

Failure

Simplest is to "simulate" the bulbs, thus using 22-33 Ohm resistors, 5W type On the other hand, most "fail safe systems" can detect lower currents too, do a larger resistor *might* also do the trick (the larger the better, since power dissipation then goes down) A bit of experimenting might help....

To possibly clarify something...I know that on the vehicle, the 55W fog lights (optional), if not fitted, were replaced with a 1000 ohm (don't know the wattage rating, etc.) resistor to override the bulb failure system. I'm trying to apply the same concept, but I don't know the appropriately rating of resistor needed for a 5W bulb. Obviously I need just enough current bridged to make the module think a bulb is in place.

Don't know if that tells you how 'sensitive' the BFM is or if it makes any difference. Not very educated in this area, just pick a little up along the way.

If the 1000 Ohm resistors work to fool the system, then it's apparently not terribly picky about matching the load. A 55 W lamp on a 14 V system (running voltage) is a load of only about 3.5 Ohms. I'd guess that the sensor is happy with pretty much any current.

If that's the case, then (with a bit of headroom) a 1000 Ohm, half Watt should work as well here as with the foggies. Do you still have those resistors?

Radio Shack should have some (SKU 271-1118). If 1K isn't in stock then try the 680 (SKU 271-1117) in the same wattage.

If your local RS is one of those cutting 'way back on the components then you can find what you need at Digikey or Jameco or Newark or Mouser or ...

I've tried many of the combinations suggested by everyone, but I'm afraid I've been unable to fool the BFM with a resistor(s). I was, however, able to wire and conceal a small 'dim' 5W bulb into the circuit...looks and works fine. Thanks for everyone's expertise!